Magnetic switch assemblage



W. C. FURNAS ET AL MAGNETIC SWITCH ASSEMBLAGE Aug. 24, 1954.

4 Sheets-Sheet 1 Filed July 21, 1951 a %1NVEN T0125 BY #6? 65% MX 54 W/T@ WII MW .1,

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Aug. 24, 1954 w. c. FURNAS ET AL MAGNETIC SWITCH ASSEMBLAGE 4Sheets-Sheet 2 Filed July 21, 1951 INVENTORS Q/a/d/ 1954 w. c. FURNAS ETAL 2,687,502

MAGNETIC SWITCH ASSEMBLAGE Filed July 21', 1951 4 Sheets-Sheet 3 157;?gmmvrozes MW; MW

6/ 19.7 TOE/VA? 491 1954 w. c. FURNAS ETAL MAGNETIC SWITCH ASSEMBLAGE 4Sheets-Sheet 4 Filed July 21, 1951 EEEEEEE IN VEN TORS mgww PatentedAug. 24, 1954 2,687,502 MAGNETIC SWITCH ASSEMBLAGE William C. Furnas,Batavia Township, Kane County, and Harold E.

signors to Furnas Electric Company,

Cobb, Aurora, 111., as-

Batavia,

111., a corporation of Illinois Application July 21, 1951, Serial No.237,948

2 Claims. 1

The present invention relates generally to improvements in switches forcontrolling the performance of other electrical equipment, and relatesmore specifically to various improvements in the construction andoperation of electromagnetically actuated switch assemblages.

The primary object of our present invention is to provide diverseimprovements in magnetic switch assemblages whereby the manufacture andinstallation thereof is simplified while their eificiency is enhanced toa maximum.

In our U. S. Patent No. 2,649,521, granted August 18, 1953, we havedisclosed an improved magnetic switch comprising a main frame providinga support for a terminal board and an inverted U-shaped laminatedmagnetic field piece having an energizing coil cooperating therewith,and a vertically reciprocable inverted T-shaped laminated armatureslidably confined within the field piece and coil and carrying movablecontacts cooperating with fixed contacts enclosed within the terminalboard, the armature being the energized coil to close the contacts andbeing reversely movable by gravity to break the circuits. While thisprior switch assemblage has proven highly satisfactory in actual use forcertain purposes, it was rather difficult to construct, assemble anddismantle some of the parts thereof, and especially the magnet, movablecontacts, and the terminal board.

It is therefore an important object of this invention to provide variousimprovements especially applicable to magnetic switches of the andremoval of parts is durable switch unit results.

Another relatively important object of the in- I vention is to providean improved electrically energized laminated magnet for motor startingswitches or the like, in which the armature is most effectively guidedduring normal operation, and wherein the armature and the fieldenergizing coil are readily removable for inspection and replacement ifnecessary.

A further important object of our present invcntion is to provide asimple but durable mount.- ing for the contacts of a magnetic switch,where.- by the fixed contacts are ported and protected while the movablecontacts are normally flexibly mounted upon the actuating armature butmay be quickly removed without removing terminals or connecting wires.

Still another important object of the present normally firmlysupinvention is to provide improved laminated armature and field pieceassemblages for a magnetic switch, in which the laminations may bestacked against the opposite sides of and secured to central assemblyplates to produce effectively cooperating elements regardless of slightvariation in thicknesses of the individual laminations.

An additional object of this invention is to provide an improved sheetmetal coil retainer for the energizing coil of a switch actuatingmagnet, the protruding ends of which may be bent to hold the coil inplace without distorting the remainder of the retainer.

Another object of the invention is to provide an improved movablecontact carrier bar for supporting the movable contacts from thearmature of a magnetic switch unit, which may be easily removed from theopen front portion of the unit without necessarily removing other partssuch as the starter switch mounting plate.

A further object of our invention is to provide an improved resettingmechanism for the overload relays associated with a magnetic switch,which will positively prevent closing of the switch contacts whileresetting is being effected but will automatically release the samethereafter.

Still another object of the present invention is to provide an improvedtwo-piece terminal board formed of insulation and adapted to normallyeliminate short circuiting and undesirable arcing by confining each setof cooperating contacts in an independent segregated enclosure, and theparts of which are readily separable to provide free access to the fixedcontacts.

An additional object of this invention is to provide improved mountingmeans for a magnetic switch or the like, which will efiectively resistand reduce objectionable vibration to a minimum, and also facilitatesinstallation of such switch units within their housings.

These and other more specific objects and advantages of the inventionwill be apparent from the following detailed description.

A clear conception of the several new features involved in the presentinvention and of the construction and functioning of a typicalcommercial magnetic switch embodying the same, may be had by referringto the drawings accompanying and forming part of this specification inwhich like reference characters designate the same or similar parts inthe various views.

Fig. 1 is a front view of one of the improved magnetic switchassemblages with the housing and terminal board covers removed showingthe movable contacts thereof in open position, and having two overloadrelays applied thereto and an auxiliary switchlet associated with eachof the opposite sides of its terminal board;

Fig. 2 is a vertical section through the housing of the switchassemblage of Fig. 1, showing a side view of the switch with thecontactsopen and the overload resetting mechanism in normal inactiveposition;

Fig. 3 is a fragment of a side view similar to that of Fig. 2, butshowing the overload relay resetting device in active position;

Fig. 4 is a horizontal section through the rear casing of the housingtaken above the switch and showing a top view of the confined switchassemblage;

Fig. 5 is a side view of the laminated magnet and armature assembly ofthe magnetic switch, a section having been taken through the magnetenergizing coil directly adjacent to the outermost laminations';

Fig. 6 is a transverse vertical section through the movable contactpusher of the laminated magnet and armature assembly, taken along theline 6-8 of Fig. 5 but with the energizing coil omitted;

Fig. 7 is another transverse vertical section taken through thelaminated magnet and armature assembly and the energizing coil, alongthe line l'l of Fig. 5;

Fig. 8 is a top view of a few of the movable contacts of the switch,showing the same applied to a fragment of the contact carrying crossarm;

Fig. 9 is an enlarged vertical section through one of the fixed andmovable contact confining chambers of the terminal board and coverassemblage, taken along the line 5-9 of Fig. 10 and showing a fragmentof one of the movable contact guides; and

Fig. 10 is a similarly enlarged transverse horizontal section throughthe terminal board and cover assemblage, taken along the line lfili! ofFig. 9 and showing all of the movable contacts confined therein.

The gist of our present invention is the provision of an improvedelectro-magnetically actuated switch unit embodying a simplified magnet,and effective contact carrying and housing structures which may bereadily manufactured, assembled or dismantled while normallysafeguarding the contacts against undesirable arcing andshort-circuiting and permitting convenient attachment of the terminalsand conductors; and while only one commercial embodiment of the improvedfeatures has been illustrated and described, it is not our desire orintention to unnecessarily restrict the utility thereof by virtue ofthis limited showing. It is also contemplated that specific descriptiveterms be given the broadest possible interpretation consistent with theactual disclosure.

Referring to the drawings, the improved electro-magnetic switch showntherein, comprises in general, an enclosing housing consisting of a rearcup-shaped casing Hi and a front cover it; a main switch s spensionframe l6 detachably secured within the casing M and having a laminatedelectro-ma-gnet ll fixedly mounted upon its lower portion and a terminalboard it likewise mounted upon its upper portion; a laminated armaturei9 cooperable with the lower poles 2B of the magnet I1, and having aninverted U-shaped pusher 2i secured to its opposite ends and supportingthree pairs of movable contacts 22 through an, insulation crossbar 23;

three pairs of stationary contacts 24 mounted within the terminal board18 and being cooperable with the movable contacts 22 to make and breakthe electric circuits controlled by the switch; a terminal board coveror closure 25 detachably secured to the board i8 and normally confiningthe contacts 22., 2% within segregated chambers 25; a thermal overloadrelay 2'! mounted upon the main frame [6 at each side of the magnet i7;and a reset mechanism for the relays 2'! adapted to positively preventclosing of the contacts 22, 24 while the relays are being reset.

The casing i4 and cover l5 of the housing are formed of durable sheetmetal and may be provided with the usual openings for the conductors andfor a starting and stopping push button switch of the type shown in ourpatent No. 2,559,777 when such a control switch is applied directly tothe cover it and frame it of the unit; and the cover 65 may also bedetachably secured to the casing M by means of lugs 29 formed on thiscasing and coacting with slots in the cover and a pair of cooperatinghasps 30 secured to the lower portions of the casing and cover, seeFigs. 1 and 2. The housing cover i5 also has an overload relay resetbutton 3! slidably confined therein by a leaf spring 32 which constantlyurges the button 3i outwardly into the position shown in Fig. 2 but maybe pressed into the position shown in Fig. 3 during resetting of therelays 21'.

The switch mounting frame it may also be formed of heavy sheet metalwith the aid of punches and dies, and is preferably provided with acentral forwardly offset stiffening area 3% and with rearwardly offsetperipheral portions 35, to provide clearance for attaching screws. Theupper offset portion 35 of the frame it is provided with a slot adaptedto cooperate with a suspension element 3? secured to the rear wall ofthe casing i i, and the lower portions 35 have holes 33 therein for thereception of retainer screws, not shown. The electromagnet ii is firmlysecured to the offset area 34 of the frame it by means of four bolts'59, while the terminal board it is likewise fastened to the frame area35 by three cap screws es coacting with metal bushings :il embeddedwithin the insulation of which the board H5 is formed see Figs. 1, 9 and10. The overload relays 2% are also mounted upon the main frame it bymeans of sheet metal brackets 2 2 and attachin screws or rivets, so thatthe entire switch unit may be readily suspended within or removed fromthe casing i l upon removal of the cover i5.

The improved laminated magnet il consists of a stiff and relativelyheavy center plate i3 having an equal number of similarly shaped sheetmetal laminations disposed on its opposite sides and secured thereto byrivets M, and has the depending opposite end poles 2i thereof embracedby shading coils 65, see Figs. 5, 6 and 7. This magnet is also providedwith an integral depending central projection it located midway betweenthe poles 28 but of less vertical length than the poles, and thisprojection it is embraced by an energizing coil i'i of approximately thesame height as the end poles 28. The annular magnet energizing coil ii?is held in position by a sheet metal inverted U-shaped retainer it whichspans the top of the magnet ii and has opposite side walls 43 extendingdownwardly through the space be tween the magnet projection 56 and theinterior of the coil 4?. Each of these side walls 49 is provided with anintegral inwardly projecting reinforcing flange U snugly engaging themagnet projection 46, and after the retainer 48 has been inserted thelower ends 5! of the walls are bent outwardly against a coil Washer 52as shown in Fig. 7 to firmly hold the coil 41 in place withoutdistorting the flanged portions of the side walls 49. The core of themagnet H is also provided with bracket plates 53 secured to the oppositeouter side laminations by the rivets 14, and which are firmly fastenedto the main frame It by screws or the like.

The laminated armature l9 which cooperates with the magnet poles 25,also consists of a central rather heavy and stiff plate 55 having a likenumber of thinner sheet metal laminations on its opposite sides andsecured thereto by rivets 56 which also clamp side plates 57 against theouter laminations. The armature I9 is of inverted T-shape by virtue ofthe provision of a central integral upwardly directed projection 58thereon, which is slidably engageable with the smooth parallel flanges55 formed on the core retainer 43 as illustrated in Figs. 5 and 7, andthe side plates 57 are provided with opposite end lugs 55 adapted tocoact with notches in the pusher 2|. When the coil 51 is energized, thearmature I8 is lifted into engagement with the magnet poles 20 so as toelevate the movable contacts 22, but upon deenergization of the magnetll the armature l9 and the elements carried thereby will promptly dropby gravity to lower the contacts 22.

The inverted U-shaped pusher 2! is also formed of sheet metal and hasopposite depending side walls 69 slidably engaging the outer surfaces ofthe magnet poles 2t and in which the notches for receiving the lugs 59are formed. A single central screw 6| coacts with the lower extremitiesof the pusher side walls 60 to clamp the lugs 59 within these notches,and upon removal of this screw 6| the walls 66 may be spread apart so asto permit free downward removal of the entire armature assembly.

relay resetting mechanism as will be explained later.

The cross bar 23 which carries the movable contacts 22 is formed ofinsulating material and springs 12 and tilting the plates H sufiicientlyto clear the flanges 10 and by thereafter lifting these mounting platesout of the guides.

The terminal board I 8 which is fastened to the main frame It by the capscrews 40 coacting with the threaded insert bushings 4|, and whichcooperates with the front closure 25 to form the contact confiningchambers 26, is of improved construction, and both this board l8 and itsclosure 25 are formed of insulating material and these elements aredetachably connected by screws 14, as illustrated in Figs. 9 and 10. Theboard I8 is provided with forwardly extending lower flanges '55 withwhich the rear flange 6'! of the cross bar 23 is cooperable tosubstantially close the chambers 26, and the interior of the board 18has integral partitions 76 adapted to coact with similarly spacedpartitions 17 formed in the closure 25 along tongue and groove joints asshown in Fig. 10, thereby effectively alining these parts andsegregating the chambers 25 from each other.

The fixed contacts 24 are suspended from L- shaped front and rearcontact carriers 18, 19 respectively each of which has an upper recesscoacting with a screw pin 80 and which are firmwithdrawing the screws'14.

A switchlet or auxiliary switch 86 of the type forming the subject of U.S. Patent No. 2,562,420, granted July 31, 1951, may also be mounted onone or both ends of the terminal board 18, in order to increase thenumber of circuits conalinement with one of the end extensions 69 of themovable contact supporting cross bar 23. These switchlets 86 willtherefore be actuated simultaneously with the main switch, and theterminal screws 88 of the auxiliary switches are also freely accessiblewhen the housing cover I5 is removed.

The overload relays 21 which are mounted upon the brackets 42 at theopposite sides of the magnet and armature assemblages, are of the typeforming the subject of U. S. Patent No. 2,597,068, granted May 20, 1952,and each of these relays has a solder pot 90 adapted to open cooperatingand the crank ends 92 of the wire 93 are constantly urged upwardly bycoil springs 97 as shown in Fig. 1. A sheet metal yoke 98 secured to andswingable with the wire 93, has a reset plate 99 attached to its medialswinging portion in line with the button 3|, and is also provided withlower extensions I60, thus completing the overload relay resettingmechanism.

The overload resetting mechanism including the button 3| mounted in thehousing cover I5, is normally positioned as shown in solid lines inFigs. 1 and 2, with the relay actuating plungers 9| in lowermostposition. When the relays 21 are sprung by an overload, the plungers 9|rise to the dot-and-dash line positions in substantial contact with thecranks 9'2 and the magnet ll will be deenergized thereby causing thearmature l9 to drop by gravity and to pull the movable contacts 22 outof engagement with the fixed contacts it as in Fig. 1. The reset button3i may then be pressed to swing the yoke 98 and wire 93 into theposition shown in Fig. 3, whereupon the crank ends 92 will force theplungers 9! of the relays 2i downwardly and will restore these relays tonormal operating osition if the overloadin has been eliminated. Whilethe button 31 is thus depressed, the mid-portion of the yoke 93 willswing over the plate (53 carried by the movable contact pusher, and willpositively prevent closing of the contacts 22; and when the button Si isreleased, the springs 32, 9'! will restore the resetting mechanism toinactive position with the yoke extensions in contact with the stopplate 65.

During normal operation of the improved magnetic switch assemblage, thestarting and stopping control switch which may be mounted eitherdirectly upon the main switch or at any other conveniently accessiblelocation remote from the main unit, may be actuated to either make orbreak the electric circuit for energizing the magnet coil it. When thiscircuit is closed by the control switch, the magnet ill quickly attractsand elevates the armature is thus causing the movable contacts 22 torise and to engage the fixed contacts 26% within the chambers 26, andalso closing the switchlets 85 if used. When the energizing circuit isopened by means of the control switch, the magnet H is promptlydeenergized thus causing the armature it to drop by gravity and to movethe contacts 22 away from the fixed contacts 25 thereby breaking themain switch circuits and those controlled by the switchlets 86. Theimproved switch is thus closed magnetically and opened by gravity at thewill of the operator, and is also effectively protected againstoverloading. It is also noteworthy that the magnetic switch may beopened by merely pressing the reset button 3!, even if the overloadrelays Z'i are not sprung.

From the foregoing description of the construction and operation of ourelectro-magnetic switch unit it will be apparent that this unit embodiesa simple, compact and durable magnetic switch and terminal boardassemblage all parts of which are readily accessible for inspection andattachment of terminals; The improved laminated magnet and armaturestructures embodying the central stiffening plates 43, 55 and the heavyside plates, may be readily assembled to properly coact with the coil4'! and with each other, even if the laminations should vary slightly inthickness; and the coil retainer 48 not only effectively holds the coilill in proper position, but it may also be easily applied and serves asa guide for the central projection 58 of the armature. The armature l9may also be readily assembled with or removed from the pusher 2| bymerely manipulating the single screw 6! and slightly bending the pusherside plates (59, and the entire magnet and armature structures areefiectively supported by the main frame it.

The movable contacts 22 while being normally mounted for most efficientcooperation with the stationary contacts 26, may be readily removed andreplaced without disturbing connections or other elements of the unitaside from the housing and terminal board covers terminal board it andits closure cover 25 cooperate with the fianged and widened crossbar 23to thoroughly conceal and protect the contacts 22, 25 within thesegregated chambers 26, and the partitions l6, ll of the terminal boardassembly permit rapid removal and replacement of the closure 25 andinspection of the contacts without releasing any terminal screws. Themovable contacts 22 may be released by merely depressing and tiltingthem sufficiently to clear the retainer flange while the fixed contacts2 1 are removable by merely releasing the screws 83 which are freelyaccessible upon removal of the terminal board closure 25.

All elements of the improved switch are sturdily' constructed ofsuitable materials so as to prevent possible objectionable arcing andshort-circuiting, and the overload relays 2'? protect the switch againstpossible damage due to overloading. The resetting of these relays 2i mayalso be quicklyand positively effected by merely pressing the button 3!without removing the cover 55, and the yoke as functions to hold thecontacts 22 open until after resetting operations have been completed.The main frame it is of simple but durable construction and may beeasily installed within or removed from the casing i l to provide aneffective three point support for the switch unit. The improved switchis especially adapted for use in electric circuits subject to strongcurrent, and requires little a tention after proper assembly andinstallation thereof.

It should be understood that it is not desired to limit this inventionto the exact details of construction and to the precise mode of use ofthe typical switch assemblage herein shown and described, for variousmodifications within the scope of the appended claims may occur topersonsskilled in the art.

We claim:

1. In an electro-hiagnet, an upright supporting frame, a laminatedmagnet core having laterally spaced upright end poles and a centralintervening shorter upright projection all formed integral with anddepending from an upper horizontal bridge piece, brackets rigidlyattached to the opposite sides of said core and having a transverse stopplate coacting with one of said end poles and flanges adjacent to theother end pole secured to said frame, an annular energizing coilsurrounding said central core projection between said end poles, aunitary inverted U- shaped sheet-metal coil retainer spanning saidbridge piece and having opposite side walls extending downwardly betweensaid core projection and the interior of said coil beyond the latter andbeing provided with integral inwardly extending flanges snugly engagingthe opposite sides of said central core projection to prevent distortionof said retainer when the downwardly extending lower wall ends are bentoutwardly beneath the coil, an inverted laminated T-shaped armaturebeneath said core and coil having a lower cross-- bar and the oppositeend portions of which are engageable with the lower ends of said polesand. also having a central upright stem slidable along said retainerflanges, and an inverted U-shaped sheet-metal pusher spanning the upperbridge piece of said core transversely of said retainer and havingdepending opposite side walls guided for upright movement along theopposite sides of the core and which are interconnected at their lowerextremities and attached to the outermost I5, 25. The improved I ends ofsaid armature cross-bar, said pusher also having a stop plate cooperablewith the stop plate of said bracket.

2. In an electro-magnet, an upright supporting frame, a laminated magnetcore having laterally end poles and a central intervening shorterupright projection all formed independing from an upper horizontalbridge piece, brackets rigidly attached to the opposite sides of saidcore, one of said brackets having a transverse plate spanning one ofsaid both of said brackets being secured adjacent to the other end pole,an annular energizing coil surrounding said central core projectionbetween said end poles, a unitary inverted U-shaped sheet-metal coilretainer spanning said bridge piece and having opposite side wallsextending downwardly between said core projection and the interior ofsaid coil beyond the latter and being provided with integral innatedT-shaped armature beneath said core and coil having a lower cross-barthe opposite end portions of which are engageable with the lower ends ofsaid poles and also having a central upright stem slidable along saidretainer flanges, and an inverted U-shaped sheet-metal pusher spanningthe upper bridge piece of said core transversely over said retainer andhaving depending opposite side walls guided for upright movement alongthe opposite sides of the core and which are interconnected at theirlower extremities and attached to the outermost ends of said armaturecross-bar.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Re. 20,094 Wilms et a1 Sept. 1, 1936 2,071,149 Wilms et a1Feb. 16, 1937 2,227,434 Bierenfeld Jan. 7, 1941 2,347,934 Christensen eta1. May 2, 1944 2,348,556 Matthias May 9, 1944 2,358,568 Furnas et a1Sept. 19, 1944 2,387,033 Matthias Oct. 16, 1945 2,399,575 SchleicherApr. 30, 1946 2,424,776 Stapleton July 29, 1947 2,434,096 Ayers et alJan. 6, 1948 2,492,726 Ayers et a1. Dec. 27, 1949 2,499,958 KnowltonMar. 7, 1950

